TYPES OF CANCER

There are more than 100 types of cancer. Types of cancer are usually named for the organs or tissues where the cancers form or by the type of cell that formed them.

The most common types of cancer diagnosed in children and adolescents are: leukemia, brain and other central nervous system tumors, lymphoma, rhabdomyosarcoma, neuroblastoma, Wilms tumor, bone cancer, and gonadal (testicular and ovarian) germ cell tumors.

Carcinoma

Carcinomas are the most common type of cancer. They are formed by epithelial cells, which are the cells that cover the inside and outside surfaces of the body. There are many types of epithelial cells, which often have a column-like shape when viewed under a microscope.

Carcinomas that begin in different epithelial cell types have specific names:

Adenocarcinoma is a cancer that forms in epithelial cells that produce fluids or mucus. Tissues with this type of epithelial cell are sometimes called glandular tissues. Most cancers of the breast, colon, and prostate are adenocarcinomas.

Basal cell carcinoma is a cancer that begins in the lower or basal (base) layer of the epidermis, which is a person’s outer layer of skin.

Squamous cell carcinoma is a cancer that forms in squamous cells, which are epithelial cells that lie just beneath the outer surface of the skin. Squamous cells also line many other organs, including the stomach, intestines, lungs, bladder, and kidneys. Squamous cells look flat, like fish scales, when viewed under a microscope. Squamous cell carcinomas are sometimes called epidermoid carcinomas.

Transitional cell carcinoma is a cancer that forms in a type of epithelial tissue called transitional epithelium, or urothelium. This tissue, which is made up of many layers of epithelial cells that can get bigger and smaller, is found in the linings of the bladder, ureters, and part of the kidneys (renal pelvis), and a few other organs.

Sarcoma

Sarcomas are cancers that form in bone and soft tissues, including muscle, fat, blood vessels, lymph vessels, and fibrous tissue (such as tendons and ligaments).

Rhabdomyosarcoma is the most common type of soft tissue sarcoma in children. It begins in muscles that are attached to bones and help the body move. Most rhabdomyosarcomas are diagnosed in children younger than 10 years. Rhabdomyosarcomas usually form lumps near the surface of the body and are found early.

There are three main types of rhabdomyosarcoma:

Embryonal: This type occurs most often in the head and neck area or in the genital or urinary organs. It is the most common type.

Alveolar: This type occurs most often in the arms or legs, chest, abdomen, genital organs, or anal area. It usually occurs during the teen years.

Anaplastic: This type rarely occurs in children.

Causes: In most cases, the cause of rhabdomyosarcoma is not known.

Radiation therapy and certain diseases and inherited conditions can increase the risk of soft tissue sarcoma. Children who had a high birth weight or were larger than expected at birth may have an increased risk of embryonal rhabdomyosarcoma.

Signs and symptoms that may be caused by childhood rhabdomyosarcoma depend on where the cancer forms. Some signs and symptoms are:

A lump or swelling that keeps getting bigger or does not go away. It may be painful.

Bulging of the eye.

Headache.

Trouble urinating or having bowel movements.

Blood in the urine.

Bleeding in the nose, throat, vagina, or rectum.

Treatment often works better in children and they may have a better chance of being cured than adults.

After childhood rhabdomyosarcoma has been diagnosed, treatment is based on the stage of the cancer and whether all the cancer was removed by surgery.

Osteosarcoma is the most common cancer of bone.

Leukemia

Cancers that begin in the blood-forming tissue of the bone marrow. These cancers do not form solid tumors. Instead, large numbers of abnormal white blood cells (leukemia cells and leukemic blast cells) build up in the blood and bone marrow, crowding out normal blood cells.

The low level of normal blood cells can make it harder for the body to get oxygen to its tissues, control bleeding, or fight infections.

Acute leukemia is a fast-growing cancer that usually gets worse quickly. Chronic leukemia is a slower-growing cancer that gets worse slowly over time. The treatment and prognosis for leukemia depend on the type of blood cell affected and whether the leukemia is acute or chronic. Chemotherapy is often used to treat leukemia.

Childhood Acute Lymphoblastic Leukemia (also called ALL or acute lymphocytic leukemia) usually gets worse quickly if it is not treated.

Acute Lymphoblastic Leukemia is the most common type of cancer in children.

Standard (low) risk: Includes children aged 1 to younger than 10 years who have a white blood cell count of less than 50,000/µL at diagnosis.

High risk: Includes children 10 years and older and/or children who have a white blood cell count of 50,000/µL or more at diagnosis.

Other factors that affect the risk group include the following:

Whether the leukemia cells began from B lymphocytes or T lymphocytes.

Whether there are certain changes in the chromosomes or genes of the lymphocytes.

How quickly and how low the leukemia cell count drops after initial treatment.

Whether leukemia cells are found in the cerebrospinal fluid at diagnosis.

The treatment of childhood Leukemia is done in phases:

Remission induction: This is the first phase of treatment. The goal is to kill the leukemia cells in the blood and bone marrow. This puts the leukemia into remission.

Consolidation /intensification: This is the second phase of treatment. It begins once the leukemia is in remission. The goal of consolidation/intensification therapy is to kill any leukemia cells that remain in the body and may cause a relapse.

Maintenance: This is the third phase of treatment. The goal is to kill any remaining leukemia cells that may regrow and cause a relapse. Often the cancer treatments are given in lower doses than those used during the remission induction and consolidation/intensification phases. This is also called the continuation therapy phase.

In Acute Myeloid Leukemia (AML), the myeloid stem cells usually become a type of immature white blood cell called myeloblasts (or myeloid blasts). The myeloblasts, or leukemia cells, in AML are abnormal and do not become healthy white blood cells. The leukemia cells can build up in the blood and bone marrow so there is less room for healthy white blood cells, red blood cells, and platelets.

When this happens, infection, anemia, or easy bleeding may occur. The leukemia cells can spread outside the blood to other parts of the body, including the central nervous system (brain and spinal cord), skin, and gums. Sometimes leukemia cells form a solid tumor called a granulocytic sarcoma or chloroma.

Lymphoma

Lymphoma is cancer that begins in lymphocytes (T cells or B cells). These are disease-fighting white blood cells that are part of the immune system. In lymphoma, abnormal lymphocytes build up in lymph nodes and lymph vessels, as well as in other organs of the body.

There are two main types of lymphoma:

Hodgkin lymphoma – These cells usually form from B cells. Most people with Hodgkin lymphoma have the classic type. With this type, there are large, abnormal lymphocytes (a type of white blood cell) in the lymph nodes called Reed-Sternberg cells. Hodgkin lymphoma can usually be cured.

In the United States, the incidence of Hodgkin lymphoma is age related and is highest among adolescents aged 15 to 19 years.

Epstein-Barr virus (EBV) and mononucleosis has been implicated in the causation of Hodgkin lymphoma.

The treatment and the chance of a cure depend on the stage and the type of lymphoma.

Childhood and adolescent cancer survivors require close monitoring because late effects of cancer therapy may persist or develop months or years after treatment.

Non-Hodgkin lymphoma – This is a large group of cancers that start in lymphocytes. The cancers can grow quickly or slowly and can form from B cells or T cells. Most types of NHL form from B-cells. NHL may be indolent (slow-growing) or aggressive (fast-growing).

Unlike adults with lymphoma, who usually have disease within the lymph nodes, children typically have disease involving outside the lymph in the mediastinum, abdomen, and/or head and neck, as well as marrow or CNS. For example, in developed countries, Burkitt lymphoma/leukemia occurs in the abdomen (approximately 60% of cases), with 15% to 20% of cases arising in the head and neck.

Burkitt and Burkitt-like lymphoma/leukemia in the United States accounts for about 40% of childhood non-Hodgkin lymphoma (NHL) and exhibits a consistent, aggressive clinical behavior. The overall incidence in the United States is is higher among boys than girls.

Mycosis fungoides and the Sézary syndrome are types of NHL that start in white blood cells in the skin. Primary central nervous system lymphoma is a rare type of NHL that starts in white blood cells in the brain, spinal cord, or eye.

Multiple Myeloma

Multiple myeloma is cancer that begins in plasma cells, another type of immune cell. The abnormal plasma cells, called myeloma cells, build up in the bone marrow and form tumors in bones all through the body. Multiple myeloma is also called plasma cell myeloma and Kahler disease.

Melanoma

Melanoma is cancer that begins in cells that become melanocytes, which are specialized cells that make melanin (the pigment that gives skin its color). Most melanomas form on the skin, but melanomas can also form in other pigmented tissues, such as the eye.

Brain and Spinal Cord Tumors

There are different types of brain and spinal cord tumors. These tumors are named based on the type of cell in which they formed and where the tumor first formed in the central nervous system. For example, an astrocytic tumor begins in star-shaped brain cells called astrocytes, which help keep nerve cells healthy.

Brain and spinal cord tumors are the third most common type of childhood cancer, after leukemia and lymphoma.

Brain Tumor Signs and Symptoms

Morning headache or headache that goes away after vomiting.

Frequent nausea and vomiting.

Vision, hearing, and speech problems.

Loss of balance and trouble walking.

Unusual sleepiness or change in activity level.

Unusual changes in personality or behavior.

Seizures.

Increase in the head size (in infants).

Spinal Cord Tumor Signs and Symptoms

Back pain or pain that spreads from the back towards the arms or legs.

A change in bowel habits or trouble urinating.

Weakness in the legs.

Trouble walking.

A rare form called atypical teratoid/rhabdoid tumor, is fast growing, signs and symptoms may develop quickly and get worse over a period of days or weeks.

Germ Cell Tumors

Germ cell tumors are a type of tumor that begins in the cells that give rise to sperm or eggs. These tumors can occur almost anywhere in the body and can be either benign or malignant.

Neuroendocrine Tumors

Neuroendocrine tumors form from cells that release hormones into the blood in response to a signal from the nervous system. It most frequently originates in one of the adrenal glands, but can also develop in nerve tissues in the neck, chest, abdomen, or pelvis.

Neuroblastomas are the most common cancer in infancy. Most often occurs in children younger than 5 years of age. Sometimes it forms before birth and is found during a routine pregnancy ultrasound.

The adrenal glands make important hormones that help control heart rate, blood pressure, blood sugar, and the way the body reacts to stress. It may also begin in the abdomen, in the chest, in nerve tissue near the spine in the neck, or in the spinal cord.

These tumors, which may make higher-than-normal amounts of hormones, can cause many different symptoms. Neuroendocrine tumors may be benign or malignant.

It is usually found when the tumor begins to grow and cause signs or symptoms. By the time neuroblastoma is diagnosed, the cancer has usually metastasized (spread). It spreads most often to the lymph nodes, bones, bone marrow, liver, and in infants, skin.

Neuroblastoma is sometimes caused by a gene mutation (change) passed from the parent to the child.

Signs and symptoms:

The most common signs and symptoms of neuroblastoma are caused by the tumor pressing on nearby tissues as it grows or by cancer spreading to the bone.

•Lump in the abdomen, neck, or chest.

•Bulging eyes.

•Dark circles around the eyes ("black eyes").

•Bone pain.

•Swollen stomach and trouble breathing (in infants).

•Painless, bluish lumps under the skin (in infants).

•Weakness or paralysis (loss of ability to move a body part).

Less common signs and symptoms of neuroblastoma include the following:

•Fever.

•Shortness of breath.

•Feeling tired.

•Easy bruising or bleeding.

•Petechiae (flat, pinpoint spots under the skin caused by bleeding).

•High blood pressure.

•Severe watery diarrhea.

•Jerky muscle movements.

•Uncontrolled eye movement.

Low-risk and intermediate-risk neuroblastoma have a good chance of being cured. High-risk neuroblastoma may be hard to cure.

Carcinoid Tumors

Carcinoid tumors are a type of neuroendocrine tumor. They are slow-growing tumors that are usually found in the gastrointestinal system (most often in the rectum and small intestine). Carcinoid tumors may spread to the liver or other sites in the body, and they may secrete substances such as serotonin or prostaglandins, causing carcinoid syndrome.

Renal Cancer

There are many types of childhood kidney tumors.

·Wilms Tumor

In Wilms tumor, one or more tumors may be found in one or both kidneys. Wilms tumor may spread to the lungs, liver, bone, brain, or nearby lymph nodes. Most childhood kidney cancers are Wilms tumors, but in children 15 to 19 years old, renal cell cancer is more common.

·Renal Cell Cancer (RCC)

Renal cell cancer is rare in children and adolescents younger than 15 years old. It is much more common in adolescents between 15 and 19 years old. Renal cell cancers may spread to the lungs, liver, or lymph nodes. Renal cell cancer may also be called renal cell carcinoma.

·Rhabdoid Tumor of the Kidney

Rhabdoid tumor of the kidney is a type of kidney cancer that occurs mostly in infants and young children. It is often advanced at the time of diagnosis. Rhabdoid tumor of the kidney grows and spreads quickly, often to the lungs or brain.